I tried to use my 2005 eMac with OS X 10.4.11 tonight, but got a "Darwin/BSD login prompt" on a black screen.

tried to use my 2005 eMac with OS X 10.4.11 tonight, but got a "Darwin/BSD login prompt" on a black screen. I did a Google search & one response to this same inquiry said to try hold down the S key. Nothing really changed. It also suggested an Option and S key hold down. Still nothing really different other than some text that said something about a 5 minute delay. How can I get my once-reliable eMac up & running again? It does acknowledge being connected to a 100 MBS cable modem router. Any suggestions please?